Answer:
Equation 1
In the story it said Eli's mom doubled the money he left, that is what the two represents. 10 is the original amount he had. -k is the money he lost.
Equation 2
20 is the the result of the original 10 being multiplied. -2k, now the 2 is still the amount that the mom doubled his amount by, and the k is how much money Eli lost.
Hope this helps!!
I think it would be 4/3 because when you multiply 8 by 4/3 you get 6 and when you multiply-6 by 4/3 you get -4.5 so
4/3
A unit is a measurement. for example, a unit could be an inch, or it could be a foot. to convert you need the exact measurement so if a line is 12 inches it's 1 foot. if it is 13 then it stays in inches. You convert units to the easiest variable to calculate and then you solve your equation from there.
Hope I helped! :)